I believe 19672217 did change the permissions to allow maintainers to
change the `reject_unsigned_commits` and `commit_committer_check`
settings even when it's enabled globally, but the controller spec wasn't
change accordingly.

Interestingly, the specs were always failing on first try (expected),
but passed on retry, probably due to rspec-retry which doesn't
completely resets the state between retries.
Signed-off-by: Rémy Coutable <remy@rymai.me>